Tens of thousands of dead fish have washed up on a 25-mile stretch of Lake Erie's northern shore, and Ontario environmental officials say they could be victims of a natural phenomenon called a lake inversion.

The inversion brings cold water, which has lower oxygen levels, to the lake's surface and fish suffocate.

"Essentially it's a rolling over of the lake," Ontario Ministry of the Environment spokeswoman Kate Jordan told The Chatham Daily News. "Something - whether it be a storm, or cooler temperatures at night, or strong winds - triggers a temperature change in the lake."

Jordan said it was windy and choppy on the lake Friday night, according to a report in The Windsor Star. The fish kill was reported Saturday.

The U.S. Environmental Protection Agency said the central basin of Lake Erie, between Cleveland on the south and Chatham, Ontario, on the north is particularly susceptible to oxygen deprivation, with the danger peaking in late August and mid-September.

Others suspect a sewage spill may have something to do with the fish kill.

David Colby, chief medical officer of the Chatham-Kent district where dead fish litter the beaches, told The Windsor Star that residents reported a strong sewage smell the night before the fish washed ashore.

‚ÄúAll kinds of people were woken out of a sound sleep by a stench and it was like a septic tank was backing up,‚ÄĚ The Windsor Star quoted Colby as saying.

But Jordan said tests of lake water taken Saturday showed no signs of what might have killed the fish. The water was tested for oxygen, PH levels, conductivity and temperature, she said.

"The ministry did not observe any evidence of a spill or pollution and water quality measurements done did not show anything unusual," Jordan told CNN.

The investigation was continuing, she said.

The dead fish included carp, sheepshead, perch, catfish and suckers, the Daily News reported, and Colby said most were of good size.

"I haven't seen anything like this in quite some time," the Daily News quoted him as saying. "The interesting thing is that most of the fish are sizable. There are very few little ones."

‚ÄúWe are having discussions with Environment Canada, the health unit and natural resources about that now,‚ÄĚ the Toronto Star quoted her as saying.

Meanwhile, residents said the smell of rotting fish is overpowering.

"I had family here (on Monday) and I didn't allow them to take the dog or the children down to the beach," Chatham-Kent resident Patricia Pook told CNN affiliate CBC News. "I knew it was bad, but the smell is just overwhelming. It would make you sick to your stomach."

I have posted several replies explaining in greater details why a fish die off ocurrs during an inversion.... I tried to make it a little more clear and correcting some misconceptions about water. Look through the comments and you will see my comments.... I doubt anyone really reads this stuff anyways... however ... to all the folks who question the dynamics of our fresh water lakes... read some science... study a little harder... I see a lot of ignorance here... sorry...

"The inversion brings cold water, which has lower oxygen levels, to the lake's surface and fish suffocate." This must be 'new science'; when I was a kid and dinosaurs freely roamed, cold water held more oxygen (or any gas) than warm water.

The deep 7.9 in Costa Rica sent recorded s-waves all the way up New Madrid fault to Lake Erie. Possible release of natural gas simular to sink hole that opened in Ontario. More 7 magnitude quakes than usual in the last week including the artic circle 7.7 then 7.6 Indonesia. Strong magnetic flux from Sept 3rd CME impact may have also cased the mass whale beachings in Fla & Scotland. Add strong winds and multi-effects create complicated reactions. Now for a fun fact: 101 days between the 11th anniversary of the 9-11 tragedy and 12-21-12 solstice.

My extended family has lived on Lake Erie since turn of the last century, in New York between Wendt Beach and Evangola State Park. Thermal inversions a a way of life on the lake. I cannot count the number of times that we saw the results of thermal inversions between our cottage and Point Breeze alone. Yes, the fish stink, and yes you spend the better part of a day burying them, maybe two days. Thermal inversions happen.

Guess where you get your bottled water from??? Yep thats right, the great lakes... I am sure that no one (especially our wonderful government) would ever do anything to hurt us americans!?!? Yeah, right!

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